An example of the triclinic crystals, microcline

In crystallography, the triclinic crystal system is one of the 7 crystal systems. A crystal system is described by three basis vectors. In the triclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. In addition, all three vectors are not mutually orthogonal.

Triclinic (a ≠ b ≠ c and α ≠ β ≠ γ )

The triclinic lattice is the least symmetric of the 14 three-dimensional Bravais lattices. It has (itself) the minimum symmetry all lattices have: points of inversion at each lattice point and at 7 more points for each lattice point: at the midpoints of the edges and the faces, and at the center points. It is the only lattice type that itself has no mirror planes.

[edit] Triclinic Crystal Classes

The triclincic crystal system class names, examples, Schönflies notation, Hermann-Mauguin notation, point groups, International Tables for Crystallography space group number^[1], orbifold, type, and space groups are listed in the table below. There are a total 2 space groups.

Crystal Class	Example	Schönflies	Hermann-Mauguin notation	point groups	#	orbifold	Type	space groups
Pedial [2]	Tantite	C1	1	1	1	11	enantiomorphic polar	P1
Pinacoidal [2]	Wollastonite	Ci (also denoted by S2)			2	1x	centrosymmetric

With each only one space group is associated. Pinacoidal is also known as triclinic normal. Pedial is also triclinic hemihedral

Mineral examples include plagioclase, microcline, rhodonite, turquoise, wollastonite and amblygonite, all in triclinic normal (bar 1).

[edit] See also

• Crystal structure

[edit] References

• Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., pp. 64 - 65, ISBN 0-471-80580-7